Heparin sorbed

Table 20 presents the results pertaining to the synthesis and properties of the gels. The gels are seen to sorb heparin from plasma solution. Their capacity (the maximal amount of heparin sorbed) increases as the mobility and accessibility of the cholesterol fragment for the macromolecules of heparin is increased by varying the length of the polymethylene spacer. The data in Table 20 illustrate that the capacity varies from 0.7 to 0.9 and 1.3 mg/mg of immobilized UChD for cholesterol esters of N-meth-acryloyl-fS-alanine (n — 2), N-acryloyl-co-aminoenantic acid (n = 6), and N-meth-acryloyl-co-aminolauric acid (n = 11), respectively. 

The sorbed heparin fully retains its anticoagulant activity the thrombin time for both sorbed heparin and heparin in solution is 20 + 2 s/mg heparin. The clotting time of blood in contact with the gel is proportional to the amount of heparin sorbed and significantly higher than that characteristic for the non-heparinized gel. Heparin may be repeatedly sorbed after it has been removed with saturated NaCl solution. 

Similar results were obtained when polyethylene was modified by grafting acrylamide and cholesterol ester of N-methacryloyl-[3-alanine to get 0.3 + 0.1 mg UChD/ cm2. The efficiency of UChD bound to polymer was close to that of UChD immobilized in a polyacrylamide gel the graft copolymers sorbed from the plasma solution the amount of 0.9 mg heparin/mg of immobilized UChD. The clotting time of blood contacting the modified (but not heparinized) polyethylene was 6 min, whereas on its heparinization the time increased to 30 minutes. The latter figure was actually unaltered after sixfold repetition of the heparin sorption, subsequent washing heparin off the polymer and its repeated sorption. 

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